A multiple antenna system may utilize spatial diversity for a given bandwidth using a beam pattern, and suppress and cancel interference generated between multiple access users. Examples of a linear beamforming technique at a transmission end include Equal Gain Transmission (EGT) that transmits the same transmission power between transmission antennas, Space-Time Block Coding (STBC), Zero Forcing (ZF) beamforming, Minimum Mean Square Estimate (MMSE), and the like. The ZF beamforming shows an excellent performance when correlation between channels of multiple accessing terminals is low, and another factor that determines a performance of the ZF beamforming is powers to be allocated to each terminal. Therefore, a high performance gain with respect to the same power allocation technique may be obtained by allocating power differently for each terminal under a limited transmission power condition.
Recently, a distributed MIMO technique or a cooperative transmission technique for performing simultaneous transmission on a plurality of terminals using antennas of geographically distributed base stations on the same channel. The number of terminals included in a multiple access terminal set needs to be smaller than or the same as the number of antennas where cooperative transmission is performed, and a ZF beamforming vector is formed through a channel inverse transform process. An interference between terminals is cancelled by the ZF beamforming, and a power allocated to each terminal is limited by a power gain by the ZF beamforming and a limit power for each terminal. A water-filling power control widely used for the conventional multiple carrier system or centralized multiple antenna system operates under a condition where a limit transmission power condition for sum of powers allocated to respective terminals is given. However, since a limit transmission power condition exists for each antenna in the case of the distributed MIMO technique, a power control technique that reflects this condition needs to be applied. According to the water-filling based power control technique, since high power is allocated when a channel gain is large and low power is allocated when a channel gain is small, there is high possibility that a minimum Signal-to-Noise Ratio (SNR) level for information transmission may not be met and so transmission-not-allowed state may exist, or a minimum transmission rate requirement condition may not be met. Therefore, a power control technique for considering transmission limit power for each antenna, and simultaneously, reducing a transmission-not-allowed probability generated in the water-filling based power control technique, and meeting a minimum transmission rate requirement condition for each terminal needs to be proposed.